A developing cartridge including a developing roller is known in the art. Such developing cartridge is mountable to an image forming apparatus.
Prior art discloses a developing cartridge provided with a gear rotatable from a first position to a second position. The gear includes a protrusion movable in accordance with the rotation of the gear to bring into contact with a lever of the image forming apparatus. The lever is moved by the contact with the protrusion. The image forming apparatus detects movement of the lever to determine a specification of the developing cartridge. The gear includes a gear teeth portion and toothless portion. The gear is rotated by a predetermined angle by the meshing engagement between the gear teeth portion and a drive gear for transmitting driving force to the gear. Upon rotation of the gear by the predetermined angle, the gear teeth portion is disengaged from the drive gear, so that the toothless portion faces the drive gear. Thus, driving force from the drive gear is not transmitted to the gear, stopping the rotation of the gear, thereby stopping movement of the protrusion.